13365( 5) - 29-Jan-2016 12:06:54 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 13365 Version: 5 Check-in Time: 29-Jan-2016 12:06:54 STScI Edit Number: 2 Title Probing the nature of small-scale structure towards rho Oph stars: A new avenue in diffuse interstellar band research ------------------------------------------------------------------------------------ Type Cycle GO 21 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Martin A Cordiner Catholic University of America Y CoI: Dr. Keith T. Smith Royal Astronomical Society N CoI: Dr. Steve J Fossey University College London N CoI: Dr. Theodore R. Gull NASA Goddard Space Flight Center N CoI: Prof. Peter J Sarre University of Nottingham N CoI: Dr. Steven B. Charnley NASA Goddard Space Flight Center N ------------------------------------------------------------------------------------ Abstract The first evidence for variations in diffuse interstellar band (DIB) strengths over distance scales as small as a few hundred AU was presented by Cordiner et al. (2013), who measured diferences of 5% - 9% in the equivalent widths of several DIBs between the close binary stars rho Oph A and B (separated by c. 344 AU). Larger differences were observed between AB and rho Oph D (separation 19, 000 AU), indicative of substantial small-scale variations in the abundances of the large molecules believed to cause the DIBs. This finding offers an unprecedented opportunity to examine the factors that control diffuse band strengths in the relatively small and controlled environment of rho Oph, in order to help resolve the 92-year-old mystery of the identities of the carriers. A secondary objective is to measure the properties of the gas responsible for small-scale structure towards rho Oph, and ascertain the cause of previously-observed atomic and molecular absorption line strength variations. This will provide important information on the nature of diffuse molecular gas in a star-forming region, of relevance to theories regarding molecular cloud formation. We propose to achieve these goals through very high-sensitivity measurements of the ionisation state, temperature, density and depletion of the interstellar gases in the sightlines towards rho Oph A, B and D through high-signal-to-noise, high-resolution observations of atoms, ions and molecules at wavelengths 117-240 nm. Primary diagnostics include the relatively-unsaturated absorption lines of C I, Fe I, Fe II and C2. ------------------------------------------------------------------------------------ Observations Description ------------------------ We require use of the high-resolution MAMA UV echelle, and aim to abtain the highest S/N possible for C$_2$ and Fe lines (while keeping the observing time request reasonable), in order to detect small differences in line strengths between our targets. We thus propose to obtain a continuum S/N of 130 in the spectral range 2124-2401~\AA\ using the E230H $c2263$ echelle setting with the NUV-MAMA detector. The $0.2''$ slit will be employed to maximise throughput and provide sufficient resolution for our science goals in this spectral region. Using the online STIS ETC with flux-calibrated user-supplied spectra of each star obtained from the IUE archive, the desired S/N can be obtained in approximately 3000~s for $\rho$~Oph~B and 5000~s for $\rho$~Oph A. 13365( 5) - 29-Jan-2016 12:06:54 - [ 2] To obtain the required C\, {\sc i} fine structure spectra at 1190-1330~\AA, as well as (relatively unsaturated) lines of O\, {\sc i}, P\, {\sc ii}, Kr\, {\sc i}, Ge\, {\sc ii}, Mg\, {\sc ii}, Mn\, {\sc ii} and Ni\, {\sc ii}, we propose to employ the E140H $i1271$ echelle setting in the FUV. Use of the $0.03''$ slit is required for observation of $\rho$~Oph A and B which, according to the ETC, have total detector count rates of 104, 000~s$^{-1}$ and 143, 000~s$^{-1}$, respectively, in the range 1170-1372~\AA. In order to discern differences in spectral line profiles at the level of a few percent, we also require reobservation of $\rho$~Oph D in the FUV using the $0.03''$ slit. Required exposure times to reach the required S/N of $\approx100$ at 1270~\AA\ are 2000~s for A, 1500~s B and 8000~s for D. To achieve highest possible resolution, we request use of the `repeller wire off setting' of the FUV MAMA. To keep within the $2'$ limit for small-angle maneuvers, we propose to observe A \& B in one visit and D in a separate visit. The STIS CCD will be used for target acquisition; counts from our (bright) targets will be restricted by use of the O\, {\sc ii} filter. Two 6-minute peakup maneuvers will be required to center the stars in the $0.03''$ slit at the start of FUV observations. The telescope pointing accuracy is $0.003''$ for a $3''$ small-angle maneuver (SAM), so an additional peakup is not required after the $3.1''$ SAM from B to A. No peakup is required for the $0.2''$ slit. ------------------------------------------------------------------------------------ 13365( 5) - 29-Jan-2016 12:06:54 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 HD147933 STAR, B0-B2 V-IV RA=16H25M35.1178S +/- 0.025", J2000 V = 5.05 1.75e-10 erg/cm2/s/A at 1320 DEC=-23D26'49.84" +/- 0.025" A; 1.20e-11 erg/cm2/s/A at 2300 A (+- 10%) Reference Frame: ICRS Comments: Coordinates from Hipparcos, calculated for J2000 including proper motion Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2000 -4.076617296962172E-4 -0.02504 0.0 ------------------------------------------------------------------------------------------------------------------------------------ 2 HD147934 STAR, B0-B2 V-IV RA=16H25M35.0338S +/- 0.025", J2000 V = 5.92 2.43e-10 erg/cm2/s/A at 1320 DEC=-23D26'46.99" +/- 0.025" A; 1.89e-11 erg/cm2/s/A at 2300 A (+- 10%) Reference Frame: ICRS Comments: Coordinates from Hipparcos, calculated for J2000 including proper motion Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2000 -0.0010027982454497348 -0.027219999999999998 0.0 ------------------------------------------------------------------------------------------------------------------------------------ 3 HD147888 STAR, B3-B5 III-I RA=16H25M24.2827S +/- 0.025", J2000 V = 6.779 3.6e-11 erg/cm2/s/A at 1320 A DEC=-23D27'36.79" +/- 0.025" (+- 10%) Reference Frame: ICRS Comments: This object was generated by the targetselector and retrieved from the SIMBAD database. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2000 -5.494165849831223E-4 -0.02089 0.0 ------------------------------------------------------------------------------------------------------------------------------------ 13365( 5) - 29-Jan-2016 12:06:54 - [ 4] Visit: 01 Visit Requirements: ORIENT 68D TO 158 D; ORIENT 248D TO 338 D On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 HD147933 STIS/CCD ACQ F28X50OII MIRROR 1 0.1 S (0.1 I S) Comments: 3x3 pixel box 18, 036 or S/N ~130 ------------------------------------------------------------------------------------------------------------------------------------ 2 HD147933 STIS/CCD ACQ/PEA 31X0.05ND G430M 4451 1 1 S (1 S) K A Comments: ETC is for 1 second integration with 52x0.05 This ACQPEAK is with 31x0.05NDA with 0.4 times the predicted count rate. 8827*0.4 = 3530 per 7 pixel high sample or S/N~59 ------------------------------------------------------------------------------------------------------------------------------------ 3 HD147933 STIS/FUV ACCUM 31X0.05ND E140H 1271 1 1818 S -MAMA A (1818 S) Comments: ETC run uses a scaled IUE large aperture spectrum (that includes flux from both HD147933 and HD147934). Scaling factor of 0.65 accounts for the contribution of HD147933, and factor 0.4 accounts for the difference in throughput between the requested 31x0.05NDA slit and the 52x0.05 slit available in the ETC. ------------------------------------------------------------------------------------------------------------------------------------ 4 HD147933 STIS/NUV ACCUM 31X0.05ND E230H 2263 1 2941 S -MAMA A (2941 S) Comments: ETC run uses a scaled IUE large aperture spectrum (that includes flux from both HD147933 and HD147934). Scaling factor of 0.65 accounts for the contribution of HD147933, and factor 0.4 accounts for the difference in throughput between the requested 31x0.05NDA slit and the 52x0.05 slit available in the ETC. ------------------------------------------------------------------------------------------------------------------------------------ 5 HD147934 STIS/CCD ACQ/PEA 31X0.05ND G430M 4451 1 1 S (1 S) K A Comments: Count rate for 52x0.05 aperture is 7685 counts/2.5 (31x0.05NDB = ND0.4 or 1/2.5) =3074 counts per 7 pixel res element ------------------------------------------------------------------------------------------------------------------------------------ 13365( 5) - 29-Jan-2016 12:06:54 - [ 5] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 6 HD147934 STIS/NUV ACCUM 31X0.05ND E230H 2263 1 2162 S -MAMA A (2162 S) Comments: ETC run uses a scaled IUE large aperture spectrum (that includes flux from both HD147933 and HD147934). Scaling factor of 0.35 accounts for the contribution of HD147934, and factor 0.4 accounts for the difference in throughput between the requested 31x0.05NDA slit and the 52x0.05 slit available in the ETC. ------------------------------------------------------------------------------------------------------------------------------------ 7 HD147934 STIS/NUV ACCUM 31X0.05ND E230H 2263 1 2941 S -MAMA A see below (2992 S) Comments: ETC run uses a scaled IUE large aperture spectrum (that includes flux from both HD147933 and HD147934). Scaling factor of 0.35 accounts for the contribution of HD147934, and factor 0.4 accounts for the difference in throughput between the requested 31x0.05NDA slit and the 52x0.05 slit available in the ETC. ------------------------------------------------------------------------------------------------------------------------------------ 8 HD147934 STIS/FUV ACCUM 31X0.05ND E140H 1271 1 2941 S -MAMA A (2941 S) Comments: ETC run uses a scaled IUE large aperture spectrum (that includes flux from both HD147933 and HD147934). Scaling factor of 0.35 accounts for the contribution of HD147934, and factor 0.4 accounts for the difference in throughput between the requested 31x0.05NDA slit and the 52x0.05 slit available in the ETC. ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ HD147933 1 STIS/CCD ACQ F28X50OI MIRROR none none none none 1 N/A II HD147933 2 STIS/CCD ACQ/PEA 31X0.05N G430M 4451 none none none none 1 N/A K DA HD147933 3 STIS/FUV ACCUM 31X0.05N E140H 1271 none none none none 1 N/A -MAMA DA 13365( 5) - 29-Jan-2016 12:06:54 - [ 6] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ HD147933 4 STIS/NUV ACCUM 31X0.05N E230H 2263 none none none none 2 N/A -MAMA DA HD147934 5 STIS/CCD ACQ/PEA 31X0.05N G430M 4451 none none none none 3 N/A K DA HD147934 6 STIS/NUV ACCUM 31X0.05N E230H 2263 none none none none 3 N/A -MAMA DA HD147934 7 STIS/NUV ACCUM 31X0.05N E230H 2263 none none none none 4 2992.0 S -MAMA DA HD147934 8 STIS/FUV ACCUM 31X0.05N E140H 1271 none none none none 5 N/A -MAMA DA 13365( 5) - 29-Jan-2016 12:06:54 - [ 7] Visit: 02 Visit Requirements: On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 HD147888 STIS/CCD ACQ F28X50OII MIRROR 1 0.1 S (0.1 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 HD147888 STIS/CCD ACQ/PEA 52X0.05 G430M 4451 1 1 S (1 S) K Comments: Use 52x0.05 aperture to match spectral resolution for Rho Oph A and B 1 sec integration yields 3600 c/resolution element 7 pixels high. ------------------------------------------------------------------------------------------------------------------------------------ 3 HD147888 STIS/FUV ACCUM 52X0.05 E140H 1271 1 1947 S -MAMA (1947 S) Comments: Utilize the 52x0.05 aperture to match the spectral resolution for Rho Oph A and B. global count rate is 57, 000 c/s ------------------------------------------------------------------------------------------------------------------------------------ 4 HD147888 STIS/FUV ACCUM 52X0.05 E140H 1271 1 2991 S -MAMA (2991 S) Comments: See 02.003 for global count rate ------------------------------------------------------------------------------------------------------------------------------------ 5 HD147888 STIS/FUV ACCUM 52X0.05 E140H 1271 1 2991 S -MAMA see below (2979 S) Comments: See 02.003 for global count rate ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ HD147888 1 STIS/CCD ACQ F28X50OI MIRROR none none none none 1 N/A I HD147888 2 STIS/CCD ACQ/PEA 52X0.05 G430M 4451 none none none none 1 N/A K HD147888 3 STIS/FUV ACCUM 52X0.05 E140H 1271 none none none none 1 N/A -MAMA HD147888 4 STIS/FUV ACCUM 52X0.05 E140H 1271 none none none none 2 N/A -MAMA HD147888 5 STIS/FUV ACCUM 52X0.05 E140H 1271 none none none none 3 2979.0 S -MAMA 13365( 5) - 29-Jan-2016 12:06:54 - [ 8] Summary Form for Proposal 13365 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures 31X0.05NDA, 52X0.05, F28X50OII, F28X50OIII ------------------------------------------------------------------------------------------------------------------------------------ Configurations STIS/CCD, STIS/FUV-MAMA, STIS/NUV-MAMA ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM, ACQ, ACQ/PEAK ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ORIENT 248D TO 338 D, ORIENT 68D TO 158 D ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements E140H, E230H, G430M, MIRROR ------------------------------------------------------------------------------------------------------------------------------------ Target Names HD147888, HD147933, HD147934 ------------------------------------------------------------------------------------------------------------------------------------